1. Field of the Invention
The present invention relates to analysis of trace elements, and more particularly a way of providing analytical services.
2. Background of the Invention
Trace elements play a role in health and nutrition that is being increasingly appreciated. A number of chemical elements that previously were thought not to have any biological role are now known to be crucial to the proper functioning of the metabolism. A prime example of such an element is cobalt, which is now known to be essential because of its role as a cofactor in vitamin B12. Another trace element whose importance has only recently come to be appreciated is selenium.
For many vitamins, minerals, some trace elements and macro components of the diet such as fat, protein and carbohydrates intakes can be accurately estimated using state-of-the-art food-frequency questionnaires when administered and analyzed by experienced epidemiologists. However, because the needed quantity of selenium in the human diet is low, and selenium varies greatly in concentration among the same foods, selenium intake cannot be accurately estimated by food-frequency questionnaires in diverse human diets such as those in the U.S.
In addition to essential trace elements, trace elements can also be important because of their toxic effects. Numerous chemical elements that appear in minute quantities in the body but do not have a natural role can exert toxic effects if their levels become excessive. An example of such an element would be lead.
Thus knowledge of the concentration of trace elements in biological materials is desirable. Previous efforts to monitor trace elements have significant disadvantages. Most analytical methods, such as atomic absorption or emission spectroscopy, require extensive sample treatment before determination to obtain a homogenous sample before the determination can be carried out. Such treatment typically involves pulverizing, blending, or other mechanical disruption of the physical structure of the sample, followed by chemical digestion with corrosive acid, alkali, and/or oxidizing agents, to obtain a homogeneous sample. Sample treatment is tedious, time-consuming, and expensive, because it requires the services of a trained technician. Furthermore, the corrosive reagents pose a hazard to the technician, and the disposal of the spent reagents can be expensive if environmental damage is to be avoided.
These factors make analyses for trace elements expensive. Industries that must perform such analyses routinely commonly contract with outside analytical laboratories to have them done, or alternatively buy the instruments and hire technicians to do them in-house. Neither of these options is practical for small-time users of analytical services. The capital outlay to buy the instrumentation can hardly be economic for such users. Contracting with an outside laboratory can also be cost-prohibitive, particularly if the trace element to be determined is not one that is done routinely by that laboratory.
Thus there is a need for a way to provide fast, accurate, and inexpensive analyses to those in need of them, where the analyses involve as little sample preparation as possible, and where to streamline workflow the analytical method is virtually the same for a wide variety of elements.
Neutron activation analysis (NAA) is an attractive possibility, because it entails minimal sample preparation and has previously been used for analysis of a variety of materials, including toenail samples for selenium. Thus far, however, neutron activation analysis has seen little use for routine analytical determinations because of its unavailability to users that do not have a significant amount of work to be done. On one hand, because it requires access to a research nuclear reactor and to sophisticated emissions counting equipment, neutron activation analysis has been far beyond the capability of the average analytical laboratory. On the other hand, analysis of the occasional sample for a user would be uneconomic for the operators of a research reactor. Thus there is a need for a way to provide neutron activation analysis of trace elements to users in an inexpensive and cost-effective manner.
The present invention provides a way to offer analytical services, and more specifically trace element determinations, to users in an economic fashion by streamlining workflow and thereby maximizing sample throughput. It provides for sending prospective customers sample containers that have known weight, and that bear identifying indicia. The customer then places a sample of the material to be tested into the container and returns the container with the sample to the provider of analytical services. The provider identifies and weighs the container, and by comparison with the original weight determines the weight of the sample contained therein. The provider then places the filled sample container in a neutron flux, whereby elements in the sample are activated and emit radiation characteristic of the elements that absorbed the neutrons. By measuring the emitted radiation the provider can then determine the weight percentage of one or more elements in the sample in a fashion well-known to those of ordinary skill in the art. The provider then communicates the results of the analysis to the customer by ordinary mail, email, fax, Internet website, or other method.